{"id":799,"date":"2007-10-05T12:18:00","date_gmt":"2007-10-05T04:18:00","guid":{"rendered":"http:\/\/note.systw.net\/note\/?p=799"},"modified":"2023-11-05T12:26:06","modified_gmt":"2023-11-05T04:26:06","slug":"802-2-llc","status":"publish","type":"post","link":"https:\/\/systw.net\/note\/archives\/799","title":{"rendered":"802.2 LLC"},"content":{"rendered":"\n

IEEE802.2 LLC(logic link control,\u908f\u8f2f\u93c8\u8def\u63a7\u5236)
\u662f\u5728HDLC\u7684\u57fa\u790e\u4e0a\u767c\u5c55\u8d77\u4f86\u7684,\u4e26\u4f7f\u7528\u4e86HDLC\u898f\u7bc4\u7684\u5b50\u96c6
\u8ca0\u8cac\u8655\u7406\u932f\u8aa4\u63a7\u5236,\u6d41\u91cf\u63a7\u5236,\u8a0a\u6846\u7a0b\u5e8f,mac\u5b50\u5c64\u7684\u5b9a\u5740\u5de5\u4f5c
\u63d0\u4f9b\u55ae\u9ede\u50b3\u8f38,\u591a\u9ede\u50b3\u8f38,\u5ee3\u64ad,\u4e09\u7a2e\u64cd\u4f5c\u65b9\u5f0f<\/p>\n\n\n\n

… <\/p>\n\n\n\n

802.2\u5c08\u6848\u7684\u5728OSI7\u5c64\u4e2d\u7684\u901a\u8a0a\u67b6\u69cb<\/strong><\/p>\n\n\n\n

layer2:data link layer\u4e2d\u7684LLC\u5b50\u5c64 <\/td> 802.2<\/td><\/tr>
layer2:data link layer\u4e2d\u7684MAC\u5b50\u5c64
layer1:physical layer<\/td>		 802.3\/802.3i\/802.3u\/802.3z\/802.3ab\/…\u7b49<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

\u904b\u4f5c\u5728data link layer\u7684LLC\u5b50\u5c64,\u8207\u4e0b\u5c64\u7684802.3(ethernet)\u548c802.5(token-ring),…\u7b49\u6e9d\u901a <\/p>\n\n\n\n

data link layer\u4e2d\u7684MAC(media access control,\u5a92\u9ad4\u5b58\u53d6\u63a7\u5236\u5c64)<\/strong>
\u5b9a\u7fa9\u5982\u4f55\u5728\u5be6\u969b\u7684\u7684\u7e9c\u7dda\u4e0a\u50b3\u9001\u8a0a\u6846,\u63d0\u4f9b\u548c\u8655\u7406\u88dd\u7f6e\u7684\u5be6\u9ad4\u4f4d\u7f6e,\u7db2\u8def\u62d3\u6a38\u5b9a\u7fa9\u8207\u7dda\u6750\u4e4b\u898f\u5247
\u63d0\u4f9b\u670d\u52d9\u7d66LLC\u5c64:frame Encapsulation(\u5c01\u88dd)\u53caframe Decapsulation(\u62c6\u88dd)
ps:\u5c01\u88dd\u8868\u793a\u5c07LLC frame\u52a0\u4e0a\u4e00\u4e9bframe header(SFD,DA,SA,Length,…\u7b49)\u53caframe tailer(PAD,FCS,…\u7b49)<\/p>\n\n\n\n

physical layer<\/strong>
PLS(Physical Layer Signaling,\u5be6\u9ad4\u5c64\u8a0a\u865f)\u8655\u7406\u4e3b\u8981\u5de5\u4f5c\uff1a
1\u5c07\u6bcf\u4e00\u7b46\u8981\u50b3\u9001\u7684\u8a0a\u6846\u52a0\u4ee5\u7de8\u78bc\u8655\u7406
2\u63d0\u4f9b\u901a\u9053\u6642\u5e8f\u3002
3\u91dd\u5c0d\u50b3\u9001\u4e4b\u8a0a\u6846\u7522\u751f\u524d\u5c0e\u90e8\u4efd\u53ca\u91dd\u5c0d\u63a5\u6536\u4e4b\u8a0a\u6846\u522a\u9664\u524d\u5c0e\u90e8\u4efd<\/p>\n\n\n\n

…. <\/p>\n\n\n\n

SAP(Service Access Point,\u670d\u52d9\u9ede)<\/strong>
\u8b93\u4e0d\u540c\u5de5\u4f5c\u7ad9\u4e4b\u7db2\u8def\u5c64\u901a\u8a0a\u5354\u5b9a\u53ef\u900f\u904eLLC\u4f86\u6e9d\u901a
\u7db2\u8def\u5c64\u4e0a\u6709\u591a\u7a2e\u901a\u8a0a\u5354\u5b9a\u540c\u6642\u5b58\u5728,\u4e14\u5404\u7a2e\u901a\u8a0a\u5354\u5b9a\u53c8\u53ef\u80fd\u540c\u6642\u8207\u591a\u500b\u5c0d\u8c61\u6e9d\u901a,\u56e0\u6b64\u7576LLC\u5f9eMAC\u6536\u5230\u4e00\u7b46\u8cc7\u6599\u6642\u53ef\u85c9\u7531SAP\u5224\u65b7\u8981\u9001\u7d66\u7db2\u8def\u5c64\u7684\u90a3\u4e00\u500b\u901a\u8a0a\u5354\u5b9a
SAP\u7684\u4f7f\u7528\u53ef\u4ee5\u7c21\u5316\u8cc7\u6599\u8f49\u9001\u7684\u8655\u7406\u904e\u7a0b\u3002

\u5404\u7db2\u8def\u5c64\u7684\u901a\u8a0a\u5354\u5b9a\u90fd\u53ef\u4ee5\u4f7f\u7528\u591a\u500bSAP\u8207\u5176\u4ed6\u5de5\u4f5c\u7ad9\u4e0a\u7684\u7db2\u8def\u5c64\u901a\u8a0a\u5354\u5b9a\u6e9d\u901a\u3002
\u6bcf\u7b46LLC PDU\u4e0a\u6709DSAP(Destination Service Access Point,\u76ee\u7684\u5730\u670d\u52d9\u9ede)\u53caSSAP(Source Service Access Point,\u539f\u59cb\u670d\u52d9\u9ede)\u4ee5\u8fa8\u8a8dLLC\u901a\u8a0a\u5354\u5b9a\u9593\u50b3\u9001\u7684\u8cc7\u6599\u5c6c\u65bc\u8ab0
\u4e00\u5c0dDSAP\u8207SSAP\u5f62\u6210\u6240\u8b02\u7684Connection(\u901a\u8a0a\u9023\u7dda),\u7531SSAP\u9001\u51fa\u4f86\u7684\u8cc7\u6599\u7d93\u904eLLC\u7684\u50b3\u9001\u4e4b\u5f8c\u4fbf\u9001\u7d66DSAP,\u53cd\u4e4b\u4ea6\u7136
DSAP\u8207SSAP\u6703\u6210\u70ba\u7368\u7acb\u7684\u901a\u8a0a\u9023\u7dda,\u5f7c\u6b64\u9593\u6240\u50b3\u9001\u7684\u8cc7\u6599\u4e0d\u6703\u8207\u5176\u4ed6\u901a\u8a0a\u9023\u7dda\u7684\u8cc7\u6599\u4ea4\u63db
ps:\u5728\u50b3\u9001\u7684\u904e\u7a0b\u4e2d\u6240\u6709\u901a\u8a0a\u9023\u7dda\u7684\u8cc7\u6599\u90fd\u5fc5\u9808\u7d93\u7531\u552f\u4e00\u7684MAC\u7ba1\u9053\u4f86\u50b3\u9001<\/p>\n\n\n\n

LLC\u8868\u982d\u6b04\u4f4d\u5982\u4e0b:<\/strong>
DSAP(\u76ee\u5730\u670d\u52d9\u5b58\u53d6\u9ede)<\/strong>:1byte,\u7528\u4f86\u8aaa\u660e\u8cc7\u6599\u6b04\u7528\u4f86\u8655\u7406\u7684\u901a\u8a0a\u5354\u5b9a,ex:\u8cc7\u6599\u6b04\u542bIPX\/SPX\u5247\u8a2d0xE0,ip\u5247\u8a2d0x06,snap\u5247\u70ba0xaa
SSAP(\u4f86\u6e90\u670d\u52d9\u5b58\u53d6\u9ede)<\/strong>:1byte,\u5b9a\u7fa9\u50b3\u9001\u8cc7\u6599\u5c01\u5305\u5c07\u4f7f\u7528\u7684\u4e0a\u5c64\u901a\u8a0a\u5354\u5b9a,\u901a\u5e38\u76ee\u7684\u8207\u4f86\u6e90\u901a\u8a0a\u5354\u5b9a\u4e00\u6a23
control<\/strong>:1or2byte,\u6709\u4e09\u7a2e
   U(Unnumbered)1byte
   I(Information)2byte
   S(Supervisory)2byte
ex
\u82e5\u7528\u5728802.3\u8a0a\u6846\u7684\u683c\u5f0f\u5982\u4e0b:
[preable|da|sa|length| [dsap|ssap|ctrl|<\/strong>data]<\/strong> |fcs]<\/p>\n\n\n\n

… <\/p>\n\n\n\n

SNAP(subnetwork access protocol,\u5b50\u7db2\u8def\u5b58\u53d6\u901a\u8a0a\u5354\u5b9a)<\/strong>
\u70ba\u4e86\u64f4\u5145IEEE802.3\u7684\u898f\u683c\u800c\u5efa\u7acb
\u5c01\u88dd\u5728LLC\u4e2d,\u4e3b\u8981\u7528\u5728IEEE802.2\u4e0a\u5c01\u88dd\u5c01\u5305,ARP\u7684\u8acb\u6c42\u8207\u56de\u8986<\/p>\n\n\n\n


header\u6b04\u4f4d\u5982\u4e0b:
code<\/strong>,3byte,\u53ef\u8b93\u4e0d\u540c\u5ee0\u5546\u81ea\u884c\u5b9a\u7fa9\u901a\u8a0a\u5354\u5b9a\u7528\u65bc\u81ea\u5df1\u767c\u5c55\u7684\u8a2d\u5099\u4e0a
ethertype<\/strong>,2byte,\u8207Ethernet II\u8a0a\u6846\u5b9a\u7fa9\u7684Type\u6b04\u7528\u7684\u662f\u76f8\u540c\u7684\u8a2d\u5b9a\u503c
ex:
\u82e5\u7528\u5728802.3\u8a0a\u6846\u4e2d\u7684\u683c\u5f0f\u5982\u4e0b:
[preable|da|sa|length| [dsap|ssap|ctrl| [code|type|data]<\/strong> ] |fcs]<\/p>\n","protected":false},"excerpt":{"rendered":"

IEEE802.2 LLC(logic link contr …<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"fifu_image_url":"","fifu_image_alt":"","_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[26],"tags":[],"class_list":["post-799","post","type-post","status-publish","format-standard","hentry","category-osi-layer2"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/posts\/799","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/comments?post=799"}],"version-history":[{"count":0,"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/posts\/799\/revisions"}],"wp:attachment":[{"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/media?parent=799"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/categories?post=799"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/systw.net\/note\/wp-json\/wp\/v2\/tags?post=799"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}